Testosterone Propionate – The Optimal Injectable Delivery System?

As Testosterone Replacement Therapy continues to become more and more mainstream, understanding optimal injectable delivery systems is a prudent course of action. One of the many options of injectable testosterone is testosterone propionate.

Testosterone Propionate Structural Formula

Testosterone propionate is a fast-acting, short half-life (2.25 days) testosterone ester. The testosterone ester determines how long it takes your body to dispose of the hormone in question and propionate is one of the shortest esters available with a testosterone base. There are enzymes in the body called ‘esterases’ which are responsible for removing the ester from testosterone. Once the ester is removed, all that is left is just the testosterone molecule itself. The longer the ester, the longer testosterone is active in the body and the less overall testosterone dosage is absorbed.

Because of testosterone propionate’s short half-life, peak blood levels can be modulated via injection frequency. When dosed daily or every-other-day (EOD) propionate can mimic the testosterone your body naturally produces. Its half-life is shorter than the longer-acting esters of cypionate and enanthate. In fact, after a single injection of 50 mg, the maximum concentration is reached after approximately 14 hours.

The chart below shows how much testosterone is absorbed and used for each 100 mg injected. Depending on the weight of the ester, the injectable formulations deliver different net bioavailable (how much can be absorbed by the body) mg amounts. For example, if you inject 100 mg of testosterone undecanoate, only 63 mg of it will be available for use by the body.

Testosterone Absorption by Formulation

100 mg of injectable as:

Approximate Free Equivalent

Testosterone Propionate

83 mg

Testosterone Enanthate

72 mg

Testosterone Cypionate

70 mg

Testosterone Undecanoate

63 mg

As you can see testosterone propionate is the most effective formulation (from a peak concentration standpoint on a mg per mg basis) found on the market today.

There have been stories the DEA/FDA may frown upon the dispensing of testosterone propionate instead of testosterone cypionate or enanthate by physicians. The reason given: “it is used more often for performance optimization like growth hormone (GH) and is a red flag”. There are numerous physicians prescribing testosterone propionate in their practices without issue. This may warrant further monitoring for any doctor using testosterone propionate. In my book, I recommend 30-50 mg of Testosterone Propionate injected every other day (EOD) as an excellent option for long term TRT administration.

The higher the injection frequency, the more important it becomes to use smaller/thinner gauge needles when administering TRT as a lifelong practice. Understanding this, 25-28 gauge needles are recommended. Depending on a person’s individual body fat %, the length of the needle should also be considered. The higher the body fat of the person, the longer the needle needs to be. Most people will require a 1.5 inch needle. Leaner individuals can get away with 1′ or perhaps even 5/16th’ needles.

To find out much more about the proper way to administer Testosterone Replacement Therapy, grab a copy of my book.